Turnover safety switch



Feb. 13, 1951 K. s. CLAPP 2,541,571

TURNOVER SAFETY SWITCH Filed Feb. 24, 1949 lnnnlul 1N VEN TOR.

Patented Feb. 13, 1951 UNITED PATENT OFF-ICE TURNGVER SAFETY "SWITCH Kenneth S. CIa QDaIIas, Tex.

Application February 24, 1949,Se1 ial No. 78,155

8 Claims. 1

This invention relates to a gravity actuated safetyswitch for engines of vehicles andaeroplanes, the engines of which employ electric current from a battery or magneto to spark plugs for igniting the gas vapors within the cylinders.

This application is a continuation-impart of my pending application Serial No. 692,895, filed 'August 24, 1946, for Safety Switch for Engine Driven'Vehicles, now-abandoned.

An object of this invention is to automatically and instantly shutoff the flow of electric current in the ignition system of the engine when a vehicle or aeroplane turns on its side or upside down so that there will be no danger of 'fire from electric sparks, which frequently causes loss of life and damage to property, by igniting the gas vapors when the carburetor is in an inverted or semi-inverted position.

Another object of this invention is to provide a positive and fool-proof connection between the ignition switch and the coil or distributor for continuous operation of the engine when it is performing its normal operation, and in case of accident by the vehicle or aeroplane turning over to immediately break the ignition circuit.

Another object of my invention is the provision in 'a safety switch of a bathe in the form of an island surrounded by a pool of current conducting material and having a transversely disposed passageway extending thereacross to provide for the direct bridging of the contacts.

Another object of my invention is the provision in a safety switch of a bafile which prevents washing of the current conducting fluid away from the contacts under severe vibrations, jolting, or sudden turns and stops of the vehicle and yet provides a free flow of the current conducting fluid the instant that the vehicle is tilted so that the switch may act immediately to cut oif the ignition.

Another object of my invention is the provision in a safety'switch which provides three electrical paths through the current conducting material from one contact to the other.

Other objects and a fuller understanding of my invention may be had by referring to the following description and claims, taken'in conjunction with the accompanying drawing, in which:

Figure 1 is a diagrammatic view of an ignition system of an engine for a vehicle or aeroplane, and showing my safety switch electrically connected in the system;

Figure 2 is a cross-sectionalview of my safety switch, taken along the line "22 of Figure "1;

2 Figure Bis a "cross-sectional view 'of my'safety switch, "taken along the line '33 of Figure '2;

"Figure 4 is an exploded view of my safety "switch, shov'ving the parts prior to assembly;

"Figure '5 is 'a "cross-sectional view of my safety switch, taken along the line 55 of Figure 1;

Figure dis a erspective View or the baffle andthe'electricalcontacts;

'Figu're '7 is an enlarged cross-sectional view "of the ba'file 'of Figure "6, taken "transversely through the open slot or passagewayan'd showing the two screw contacts; and 'Figure'8isaview similar to Figur'e'3,'-but"shows theswitch is a tilted position with the electri- Hundreds of ."people have been burned to death while riding in "a Vehicle or aeroplane which 'a'ccideritly turned "over or crashed and the driver "or pilot was temporarily unconscious because of "shock "or injury "so that he was unable to turn :ofi. 'the'igniti'on' switch and gasoline or other "comb'ustible motor fuel leaked from the carburetor, broken fuel lines'or gas tank'onto the distributor, generator or "shatteredwires and "caused instantaneous fire. engine 'fuel fire'spreads rapidly "and engulfs "the passengers rapidly before they can regain consciousness. V I

ignition "safety switch will definitely enmmate 'a'll fires caused loythe engine continuing to 'run after an accident wherein the vehicle "or aeroplane 'is'overturned to any angle that might cause the motor fuel to leak from an "inverted 'carbu retor, fuel tank or broken 'fuel *condu'itsfto "any "electrical sparks of the "engine.

safety switch "or circuit breaker "will not deteriorate from use, is always positive in action when an accident occurs, and is an economical device for all types of vehicles and. aeroplanes.

In the present specification and claims, the termengine driven vehicle will'be used to designate 'both aeroplanes and engine driven vehicles such as automobiles, trucks and other "vehicles employing engine's for driving power.

The i igu're '1 shows 'the preferred method of application of my safety switch, "which is designated by the reference character 10, "to the ignition system of an engine for an engine driven vehicle. The ignition system, as shown diagrammatically in Figure 1, comprises a'source of ourrent H an ignition "switch 12, a hightensionfc'oil '13, a'distributor f4 having distributing conductors leading to spark-plugs t5. Theother parts'of the electrical wiringof the engine are notshown, such as the starter, relays, and lighting circuits. 'The source ofour'rent l1 'mayco'mprise a battery or a magneto. The high tension coil l3, distributor M, or the spark plugs l may be characterized as high tension elements. Although as my preferred embodiment I have shown my safety switch I!) positioned in the primary circuit between the coil IS and the distributor I4, it will be readily understood that my safety switch |ll may be positioned in any other place to cut off the ignition when the vehicle is tilted or turned over.

My safety switch Ill comprises generally a container 21, a mounting plate 18, a clamp IQ for mounting the container 21 on the mounting plate I8. The mounting plate I8 upon which the switch It) is mounted may be the firewall or bulkhead panel separating the engine compartment from the passenger compartment. The switch I0 need not necessarily be mounted on the firewall or bulkhead panel, but may be mounted on a separate plate suitably fastened to the block or other part of the vehicle. As illustrated in Figure 5, the clamp |9 may be fastened to the mounting plate [8 by means of screws 20 which extend through the plate I8 and which are anchored thereto by means of nuts 2| and lock washers 22. The back side of the container 21 is provided with two reinforcing ribs 41 and 48 which press against the mounting plate I8 as the clamp |9 draws the container 21 toward the mounting plate. The ribs 41 and 48 reinforce the wall of the container and prevent the container from becoming distorted.

The top of the container 21 is provided with a closure cap 28. Any suitable means may be employed to securely fasten the closure cap to the top of the container, and to this end I provide an annular groove 46 on the underneath side of the cap which telescopically fits over the upper edge of the container. In order to provide a permanent water-proof seal between the cap and the container, the cap is bonded to the container by a suitable bonding material placed in the annular groove, after which the cap is pressed on tight with the bonding material thereafter setting to make the permanent bond.

The container 21 and the closure cap 28 are preferably constructed of molded polystyrene which is transparent so that one may observe the mercury within the container 21. The polystyrene has substantially zero porosity and thus prevents any moisture passing into the container.

Mounted in the bottom of the container 21 is an electrical insulating block or bafiie 29 which is constructed of material having a high dielectric strength. As illustrated in Figures 6 and '7, the baflie 29 comprises a base 40 having mounted thereon two upright posts 4| and 42, between which posts is a transversely disposed passageway 39. The insulating bafile 29 is anchored to the bottom of the container 21 by means of two screws 39 and 3| which operate as two spaced electrical contacts bridged by the current conducting fluid 38 such, for example, as mercury, provided in the lower part of the container 21. The two contact screws 30 and 3| extend through openings 44 and 45 in the bottom of the container 21. Terminals 33 and 34 are respectively connected to the contact screws 30 and 3| and, as shown in Figure 1, the terminal 33 is connected to the coil l3 by means of a conductor l6 and the terminal 34 is connected to the distributor by means of a conductor H. In mounting the terminals 33 and 34 to the contact screws 30 and 3|, I first employ a star washer 32 which fits between the bottom surface of the container and the top surface of the terminals. The terminals are then each secured to the contact screws by means of a lock washer 35 and two nuts 36 and 31, the nut 31 acting as a lock nut to insure permanent mounting and thus preventing the terminals from becoming loose. Upon the tightening of the nuts 36 and 31, the insulating bafile 29 is firmly held down against the inside bottom surface of the container 21 to seal the container against moisture entering the container and against leakage of the mercury therefrom.

As shown in Figure 'l, the openings 50 and 5| in the base of the baffle 29 through which the contact screws 30 and 3| threadably extend are tapered at their entrance end to enable the screws to be wedgingly pressed into the holes for easily starting and making their own threads. The contact screws 30 and 3| thus remain threadably fastened to the bafille 29. To provide proper electrical insulating properties, the bafiile 29 is constructed of molded phenolic which has a high dielectric strength. The drawings are drawn substantially to scale and the clearance between the outside surface of the base 40 of the bafiile 29 and the inside surface of the con tainer is slightly less than of an inch; the clearance between the outside arcuate surface of the posts 4| and 42 and the inside surface of the container is slightly greater than of an inch, and the width of the passageway 39 is approximately of an inch. The top surface of the two posts 4| and 42 extends slightly above the level of the mercury 38. The baflle 29 is in the form of an island surrounded by a pool of mercury. The flow of current from one contact to the other may be directly through the mercury which fills the transversely disposed passageway 39, or the current may flow in a divided path between the contacts by flowing around the annular pool of mercury between the outside arcuate surface of the posts 4| and 42 and the inside surfaces of the container. In other words, the design of my bafiie is such that there are three electrical paths through the mercury between the contacts 30 and 3|. Should one of the electrical paths be interrupted, there are still two electrical paths for bridging the contacts. Moreover, should two of the electrical paths be interrupted, then there is still one electrical path for bridging the contacts. With the container in an upright position, it is substantially impossible to shake the container and break all three electrical contacts at once. Actual tests show that no amount of vibration, jolting, sudden turning or quick stopping of the vehicle is sufficient to break all three of the electrical paths at once, and thereby interrupt the ignition circuit. The action of my baffle 29 is such that it prevents the washing of the mercury away from the contacts under severe vibration, jolting, and sudden turns and stops of the vehicle, and yet provides a free flow of the mercury the instant that the vehicle is tilted so that the switch acts immediately to cut off the ignition. Without being bound by the consequences of a theory, reasons may be advanced why my bafll is so efiective in preventing washing of the mercury away from the contacts. One reason which may be advanced is that just as soon as the mercury which is in the transverse passageway 38 tends to splash out it is immediately replenished by the mercury which is in the annular or circular clearance space 43 between the outside surface of the posts 4| and 42 and the inside surface of the container.

Anotherexplanation "why my baffle is effective in preventing themercur'y from be-ing washed away from the contacts is the fact that the mercury within the pasageway 39 can not readily wash into the annular =or circular clearance space '43 because the -circular space isalready (filled. That is to say, the mercury within the passagewaySS mercury holds the mercury in the pasa'geway '38 :from washing away from the contacts. noted that theends of the passageway 39 terminate Lin enlarged arcuate areas whereby'the screw 'headsffor the crew contacts maybe inserted into it is the openings 50 and 5| in the base-of the bafiie. The enlarged arcuate side walls through which the heads of the screws pass provide an extra volume of mercury directly over the screw heads and :this extra volume of mercury offers resistance to being readily washed away because the width between the enlarged arcuate side walls above the screw heads is greater than the width between the side Walls of the passageway 39. As the mercury is urged or caused to be washed back and forth-in the passageway 39, it must restrict itself asit leaves theenlargedspace above the screw heads and enters the space between the straight side walls of the passageway.

The switch is preferably mounted on the vehicle in such position that the passageway 39 is transversely disposed with respect to the vehicle, and thus when the vehicle tilts sideways,

the switch will be as shown in Figure 8, with the mercury breaking the contacts.

In service, my safety switch operates as follows: When a vehicle driver or aeroplane pilot starts the engine by turning on the switch [2, the electrical current flows from the source of current I l to the spark plugs and ignites the gas vapors within the cylinder. When a vehicle operator or aeroplane pilot has any type of accident which causes the vehicle or aeroplane to land in an inverted or semi-inverted position, the mercury or current conducting fluid flows toward the opposite end of the container 21, thereby breaking the electric current between terminals and instantly stopping the engine. This action takes place before any gas vapors could escape from an inverted carburetor or broken gasoline line or tank. A switch to be satisfactory for this type of service must be such that there is free flow of the fluid the instant that the car is tilted so that the switch may act immediately to cut on the ignition. It must be remembered that it takes less than a thousandths part of a second to cause a fire or explosion. Therefore, there must be no time delay in the free performance of the flow of the mercury. Yet at the same time, the switch must give such performance that excessive vibrations do not cause the circuit to be interrupted to cut off the ignition. If the circuit should be interrupted for a very brief interval resulting from vibration there is apt to be serious damage resulting from the danger of explosion of unburnt gases in the exhaust manifold and pipe even to the extent of blowing off the mufiler. If unburnt gas is pumped into the exhaust manifold and the exhaust pipe and then with the restoration of ignition these unburnt gases immediately explode, serious damage will result. My switch solves a problem wherein ex- 6 treme conditions must be met substantially within "a brief periodof less than a very small fraction of a second.

Although the invention'has been described in its preferred 'form with a certain :degree of particularity, it is understood that the present disclosure of the preferred form has been made only by way of example and that numerous changes in the-details o'f-construction and the combination and arrangement o'f parts maybe resorted to without departing from the spirit "and the scope of the invention as hereinafter claimed.

1 'cla'im as my invention:

1'. A gravity actuated ignition cut-cit switch for an engine driven vehicle having an ignition system, said switch comprising a container mountable on said vehicle and tiltable therewith, spaced electrical terminals attached to the bottom portion ofsai'd container and electrically in- 'sulated from 'e'achother for connection in said ignition system, current conducting fluid positioned in the bottomof said-container-and electrically bridging said spaced terminals when the engine driven vehicle is i'n-an operating position, baffle means positioned in 'thebottom portion of said container to prevent washing of the current conducting "fluid, said baflie and container providing at least three -electrical paths through said current conducting "fluid for "bridging said contacts, said bafiie having internal wall means'extending thereacrossdeflnin'g-one of said paths and having first and second external side walls respectively spacedirom said containerdefining the other two of said paths.

'2. A gravity actuated ignition cut-oi? switch for an engine driven vehicle "having an ignition system, said switch comprising 'a container mountable on said vehicle-and tiltable therewith, spaced electrical terminals attached to the bottom portion "of said container and electrically insulated from each other for connection in said ignition system, current conducting fluid positioned in the bottom of said container and electrically bridging said spaced terminals when the engine driven vehicle is in an operating position, bafile means positioned in the bottom portion of said container to prevent washing of the current conducting fluid, said bafiie and container defining an annular space with a transversely disposed passageway extending thereacross for the current conducing fluid to provide at least three electricalpaths for bridging said contacts.

3. A gravity actuated ignition cut-off switch for an engine driven vehicle having an ignition system, said switch comprising a container of transparent material mountable on said vehicle and tiltable therewith,a baffle mounted in the bottom of the container, spaced electrical terminals mounted on the bafile and extending externally from the bottom of the container for connection in said ignition system, and current conducting fluid positioned in the bottom of said container and electrically bridging said spaced terminals when the engine driven vehicle is in an operating position, said baffle and container defining an annular space with a transversely disposed passageway extending thereacross for the current conducting fluid to provide at least three electrical paths for bridging said contacts.

4. A gravity actuated ignition cut-off switch for an engine driven vehicle having an ignition system, said switch comprising a container of transparent material mountable on said vehicle and tiltable therewith, a baflle mounted in the bottom of the container, spaced electrical terminals mounted on the baffle and extending externally from the bottom of the container for connection in said ignition system, and current conducting fluid positioned in the bottom of said container and electrically bridging said spaced terminals when the engine driven vehicle is in an operating position, said baffie and container defining an annular space for the current conducting fluid to surround the baffle, said baiile comprising at least two upright posts with a passageway therebetween and providing direct communication for the current conducting fluid to bridge said terminals, said posts having sides respectively spaced from the container and defining two additional paths for the current conducting fluid to bridge said terminals.

5. A switch comprising a container, spaced electrical terminals in said container, current conducting fluid in said container, and baflie means in combination with said container for providing at least three electrical paths through said current conducting fluid for bridging said contacts, said baiile having internal wall means extending thereacross defining one of said paths and having first and second external side walls respectively spaced from said container defining the other two of said paths.

6. A switch comprising a container, spaced electrical terminals in said container, current conducting fluid in said container, and bailie means comprising at least two upright posts with a passageway therebetween and providing direct communication for the current conducting fluid to bridge said terminals, said posts having sides respectively spaced from the container and defining two additional paths for the current conducting fluid to bridge said terminal.

7. A switch comprising a container, spaced electrical terminals in said container, current conducting fluid in said container, and battle means comprising at least two upright posts with a passageway therebetween and providing direct communication for the current conducting fluid to bridge said terminals, said passageway having oppositely disposed wall surfaces with certain oppositely disposed portions thereof spaced farther apart than other portions, said posts having sides respectively spaced from the container and defining two additional paths for the current conducting fluid to bridge said terminals.

8. A switch comprising a container, spaced electrical terminals in said container, current conducting fluid in said container, and bafile means comprising at least two upright posts with a passageway therebetween and providing direct communication for the current conducting fluid to bridge said terminals, said passageway having oppositely disposed Wall surfaces with the oppositely disposed wall portions at the entrance ends thereof spaced farther apart than the intermediate portions, said posts having sides respectively spaced from the container and defining two additional paths for the current conducting fluid to bridge said terminals.

KENNETH S. CLAPP.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,638,132 Walker Aug. 9, 1927 1,726,426 Disteli Aug. 27, 1929 1,827,072 Cramblet Oct. 13, 1931 2,192,262 Griesedieck Mar. 5, 1940 2,192,797 Muter g Mar. 5, 1940 2,451,107 McCabe Oct. 12, 1948 2,451,751 Kronmiller Oct. 19, 1948 

